Mean Mr. Mustard by The Beatles is a quirky, whimsical tune that describes an eccentric and miserly man named Mr. Mustard. The song paints a vivid picture of his odd habits and stinginess. It conveys themes of loneliness and the absurdity of extreme frugality, capturing the essence of his isolated and rather pitiful existence. Particularly poignant moments in the song include the descriptions of Mr. Mustard sleeping in the park to save money and the detail that his sister, Pam, seems to be his only human connection, highlighting his solitary life.